In general, a portable device such as a portable game machine includes a first housing and a second housing. The second housing is rotatable with respect to the first housing between an overlying position in which most of the entirety of the second housing overlaps the first housing and a deployed position in which most of the second housing does not overlap the first housing.
There are two modes for rotating the second housing with respect to the first housing. In one mode, the second housing is rotated with respect to the first housing in a plane in which the first housing and the second housing contact each other when the second housing is in the overlying position. The first housing and the second housing are connected such that the first housing and the second housing are mutually rotatable about a rotation axis perpendicular to the said plane. In the other mode, the second housing rotates with respect to the first housing about a rotation axis lying in the plane in which the first housing and the second housing contact each other when the second housing is in the overlying position. The present invention relates to a portable device adopting the former mode. One example of such a portable device is disclosed in the following Patent Document 1.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-312476